Optical glass and process for its production



. Patented Sept. 18, 1956 icon and alkaline metals, such anum, zinc, indium,

tantalun, germanium, tungsten and itional substances used in relatively ot saifect the optical properties of the the percentage relationsuch as to bring it to the le tellurium trioxide (TeOs) or a mixture of tellurium oxide (TeOz) and tellurium trioxide (TeOa) either with or without addi- When tellurium ygen is given he ladvantage barium, and the oxides of sil 2763559 as sodiumgand the oxides of lanth OPTICAL GLASS AND PROCESS FOR ITS titanium, thallium,

PRODUCTION bismuth. Such add g, Marbui'g (Lahn), and Norbert 5 sinau amounts do n Meinert, Munchhausen, Kreis Marburg, Germany, asg signors to Ernst Leitz G. Wetzlal. (Lahn), The coloring of tellur um oxide can be strongly de- G a corporation of G creased if a higher oxide is used, No w g pp ca o No b 6 1951 ship to the aluminum oxide being n em er Serial No. 255,131 i 10 equivalent amount of dioxide, for examp Claims priority, application Germany November 10, 1950 f d h 1 h d tions 0 inorganic peroxi es suc as it ium peroxi e, 2 Claims (CL 106 47) sodium peroxide and barium peroxide. Our present invention relates to an optical glass contriOXide Or an iIlOTgaIlic Pemxide is used 0X sisting essentially of tellurium oxide and ofi at the higher temperatures which has it of obviating any reduction of the tellurium United States Patent '0 aluminum oxide.

When either tellurium oxide or aluminum oxide alone oxide to telis melted and cooled below its melting oi t neither lurium or to other oxidation stages than tellurium diforms a clear amorphous glass but crystalizes, N ither oxide with a consequent avoiding of any coloring efiects. can of itself be considered a glass forming compound. The melting temperatures of these glasses lies between We have found, however, that if tellurium oxide is melted 750 C. and 900 C. Through the addition of cryolite with aluminum oxide in the proportions or percentages or similar materi als one can succeed in making the melt (TeOz) to In order to obtain specific melts it is recomg melt may b mended to melt in a gold crucible, which is practically perature to ordinary atmosnot attacked. If one desires a certain aluminum oxide content in the melt, one can melt in a sintered corundum crucible; then the content of A1203 is dependent on the duration of the heating and the temperature.

0 3 www a m mm 6 m dm ad 6 se mst Ha .lwm 0 t wmffii 1 ew mm mmfi m OX P.1C f m gm 1 .mb mm %m SF y j en a mdo s9 ms mw l l ga m .1 .1 wwm m hx mv emi eun r rdl-l uop la f m PX a aO a o e mfi md mm mm m c umg .l 01 flmffi.m1m 6f mimbomT by weight of 59.5 to 93.5 of tellurium oxide 3.6 to 7 of aluminum oxide, the resultin cooled below its fusion tem Qwartz crucibles are attacked less.

By way of example melts of almost pure tellurium (4)- oxide (TeOz) are cited in Table 1. The content of aluminum oxide is essential. In Table 2, for example, melts Remarks flu NaiOz 22. 7 A1203, Crucible. 22.4 A1203, Crucible. 18.2 Pt, Crucible.

3.6 21036 1.8 1.9831 20.9 A1203, Crucible.

In Table 3 melts of the listed oxides with tel- TaaOs LiF CaF: SrFz Table J.-Percent by weight in runs TeOz Table 2.--Percent by weight in runs with various fluorides of alkali and alkaline earth metals are listed.

mixture of tellurium (4)-oxide and tellurium (6)-oxide is shown.

Melt No.

Melt No.

essentially or predominantly of a melt of tellurium oxide and aluminum oxide within the above ranges and it may also contain for any special purpose slight or small amounts of oxides, or of fluorides, which decompose to 35 lurium (U- are shown and in Table 4 melt of oxides in the melt. Examples of such additional substances are fluorides of lithium, calcium, strontium and GeOi Table 3.Percent by weight in runs TeO:

Meit No.

The compositions are not to be limited,- aoc'ordin'gto the invention, to the above-examples. The essential inventive thought coinp'iises that more than 50' per cent by weight of tellurium oxide are tobe melted to a glass With oxides of group III of the periodic table necessary to the glass'formation, with for example aluminum oxide or, in 'given cases, with oxides and/or fluorides.

aving described our invention, What we claim is:

-I. Optical glass"consisting.essentially ofelements in the fduowingrange b'y percentages b'y Weight:

and the remainder consisting of at least one member of the group of oxides lanthanum, zinc, indium, titanium,

thallium, tiantalun, germanium, tungsten and bismuth and the fluorides of lithium, calcium, strontium [and barium. 2. An optical glass consisting essentially of tellurium oxide and aluminum oxide in the mol proportion of about 9 References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Journal American Ceramic Society, vol. '30 (1947) pages 277-281.

Nor-ton: Elements of Ceramics l952), pages '148-150 and 155. 

1. OPTICAL GLASS CONSISTING ESSENTIALLY OF ELEMENTS IN THE FOLLOWING RANGE BY PERCENTAGE BY WEIGHTS: 